In the powerful position Mr Vaz held at the House of Commons his department was involved in law-making, including rules on immigration, prostitution and drugs.

Scotland Yard released a statement on Friday saying: "Following allegations in the Sunday Mirror on Sunday 4 September concerning a Member of Parliament, the Metropolitan Police Service can confirm a letter was received on Wednesday, 7 September requesting police consider the matter.

"The letter has been forwarded to the Met's Special Inquiry Team, part of Specialist Crime and Operations, to assess and identify what criminal offences - if any - may have been committed.

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MP: Keith Vaz is the Member of Parliament for Leicester East

"At this stage a police investigation has not been launched."

Tory MP Andrew Bridgen, who has been highly critical of Mr Vaz, said he would be writing to Scotland Yard calling for him to be investigated for misconduct in public office.

He also suggested Mr Vaz be investigated for conspiracy to supply illegal drugs.

Announcing his resignation, the Mr Vaz said: ""It is in the best interest of the Home Affairs Select Committee that its important work can be conducted without any distractions whatsoever.

"I am genuinely sorry that recent events make it impossible for this to happen if I remain Chair. I have always been passionate about Select Committees, having served as either Chair or Member for half of my time in Parliament.

"The integrity of the Select Committee system matters to me.

"Those who hold others to account must themselves be accountable."

He at first suggested that he was the victim of a "press sting".

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MARRIED: Keith Vaz and his wife Maria Fernandes at their wedding in London in 1993

But his resignation came after the Mirror newspaper published transcripts of a recording of the MP talking with two escorts on August 27.

The tape also reveals the MP telling an escort "treat me like a b****".

He allegedly met the men in a flat he owns near his family home in north London last month.

Mr Vaz maintains that his resignation is purely to uphold the "integrity of the select committee system".

The politician has recieved support from ex-London mayor Ken Livingstone, who is engulfed in his own scandal over controversial remarks linking Nazis to Zionism.